My system currently mirrors the one you are planning: Vandy 3A Sig's with a pair of 2Wq subs and the Model 5 crossovers (with RCA input jacks). In response to your questions (as best I can answer them):
1. The Model 5 crossover can be purchased with either the XLR or RCA input jacks. Unless you will have a LONG run from your preamp to the crossover (say, 10 feet or more) and an equipment setup that generates quite a bit of interference, there is no particular advantage to the XLR model, and you might as well save the $200.
2. Essentially you are correct -- using the adaptor will negate the signal gain achieved by the balanced inputs. If you plan to use an adaptor, you should simply buy the crossover with the RCA inputs.
3. I think your analysis of the electrical characteristics is correct, but let me add an additional point. By varying the settings on the "DIP" switches on the two crossover boxes, you can vary the impedance, thereby changing the bass response of the subwoofer(s). My Bryston 4B-ST has a nominal input impedance of 50k ohms, but my Vandy dealer recommended that I try the impedance settings both one step above and one step below the one designated for 50k ohms to see which I preferred. Initially, I preferred the impedance setting one step lower than 50k ohms, but after listening to my system for some time, and adjusting the "Q" setting and the sensitivity setting for the 2Wq subs, I finally decided that the 50k ohm setting sounded best in my room. Therefore, I suggest you follow the same procedure while "tweaking" the quality of the sound.
Best regards, and enjoy the new sub(s).
1. The Model 5 crossover can be purchased with either the XLR or RCA input jacks. Unless you will have a LONG run from your preamp to the crossover (say, 10 feet or more) and an equipment setup that generates quite a bit of interference, there is no particular advantage to the XLR model, and you might as well save the $200.
2. Essentially you are correct -- using the adaptor will negate the signal gain achieved by the balanced inputs. If you plan to use an adaptor, you should simply buy the crossover with the RCA inputs.
3. I think your analysis of the electrical characteristics is correct, but let me add an additional point. By varying the settings on the "DIP" switches on the two crossover boxes, you can vary the impedance, thereby changing the bass response of the subwoofer(s). My Bryston 4B-ST has a nominal input impedance of 50k ohms, but my Vandy dealer recommended that I try the impedance settings both one step above and one step below the one designated for 50k ohms to see which I preferred. Initially, I preferred the impedance setting one step lower than 50k ohms, but after listening to my system for some time, and adjusting the "Q" setting and the sensitivity setting for the 2Wq subs, I finally decided that the 50k ohm setting sounded best in my room. Therefore, I suggest you follow the same procedure while "tweaking" the quality of the sound.
Best regards, and enjoy the new sub(s).